A mechanical switch contact for bipolar interruption for a tap changer is known from DE-PS 100 50 821 [U.S. Pat. No. 6,740,831]. The known mechanical switch contact has an insulating support on which fixed contacts are arranged that have crowned-shaped contact areas. Furthermore, rotatably mounted on this insulating support is a contact carrier that is in contact with a pivot arm that can pivot through a certain angle. Attached at the free end of the pivot arm is a contact piece that itself has contact rollers at each of its ends. The fixed contacts can be switched as desired using these contact rollers. Depending on the position of the pivot arm, the contact rollers encounter the crowned surface of corresponding fixed contacts arranged opposite thereto and electrically connect these to one another.
This mechanical switch contact has proven itself in practical use; however, it has disadvantages during bipolar interruption of very high current. For one thing, with the above-described structural configuration of the crowned-shaped fixed contacts and the pivotal contact rollers, undesired contact impacts can occur, and in addition in this bipolar interrupting design there are high current forces that reduce the pressure of the contact rollers against the fixed contacts. The reason for this is the physical effect that reducing forces occur due to the current reduction on the narrow locations of a surface contact.